Bioleaching of a polymetallic sulphide mineral by native strains of Leptospirillum ferrooxidans from Patagonia Argentina

Two strains of Leptospirillum ferrooxidans were isolated from samples taken from La Silvita polymetallic sulphide mine, Neuquen, Argentina. Isolates were identified by 16S rRNA gene restriction enzyme analysis. The specific growth rate ( μ) at different temperatures and pH values were examined. The potential of two isolates to assist the leaching process using a mineral ore from the same mine was evaluated. The tests were carried out in shake flask at 1% (w/v) pulp density. The main sulphides found in the mineralogical composition of La Silvita ore were: sphalerite, galena, pyrite and chalcopyrite. Zinc and copper recoveries with a native isolate were 100% in 20 days and 12 days, respectively. Iron solubilization was 42% after 33 days of operation. These values were greater than those obtained using a laboratory reference strain, L. ferrooxidans DSMZ 2705, or abiotic conditions.